Recently, large-capacity exchangeable information recording media, and disc drive apparatuses which handle large-capacity exchangeable information recording media, are widely used. As large-capacity exchangeable information recording media, optical discs (e.g., DVDs, etc.) are well known.
In optical disc drive apparatuses, information is recorded onto an optical disc by forming small pits thereon using laser light. Therefore, optical disc drive apparatuses are capable of recording large-capacity exchangeable information. Optical discs have a disadvantage of exchangeable information recording media that the recording surface is likely to suffer from defects, such as dust, scratches, or the like.
To cope with this problem, optical disc drive apparatuses have to perform defect management in order to secure the reliability of recorded or reproduced data.
In a conventional defect management technique, two defect management areas (DMA) are allocated at predetermined positions in each of the inner and outer peripheries of a rewritable optical disc (i.e., a total of four DMAs are provided). If defect management information is updated, new defect management information is rewritten into these defect management areas (e.g., Japanese Laid-Open Publication No. 5-006626).
FIG. 23 shows the data structure of a conventional rewritable optical disc 400.
A data area 5 contains a user data area 16 for recording/reproducing user data, and a spare area 17 for providing a block (hereinafter also referred to as “replacement block”) which replaces a defect block present in the user data area 16. The spare area 17 is provided in advance.
A lead-in area 4 and a lead-out area 6 each contain defect management areas for recording information about a defect block present in the data area 5. The lead-in area 4 contains a first defect management area 10 (hereinafter also referred to as “DMA1”) and a second defect management area 11 (hereinafter also referred to as “DMA2”). The lead-out area 6 contains a third defect management area 12 (hereinafter also referred to as “DMA3”) and a fourth defect management area 13 (hereinafter also referred to as “DMA4”).
Each of the DMA1 to the DMA4 has a predetermined position and a fixed length. Management information provided in each of the DMA1 to the DMA4 has a length which varies depending on the number of defect blocks, i.e., a variable length. Note that all of the DMA1 to the DMA4 have the same information, i.e., a multiple of pieces of the same information are stored on a disc. This is because defects may occur in the DMA1 to the DMA4 themselves. For example, if information cannot be reproduced from a DMA but information can be reproduced from any one of the DMA1 to the DMA4, the defect management information can be obtained.
The DMA1 to the DMA4 each contain a disc definition structure (hereinafter also referred to as “DDS”) 14 and a defect list (hereinafter also referred to as “DFL”) 15, where the DDS 14 precedes the DFL 15.
The DFL 15 contains a defect list header 32 and M defect entries 33 (M: an integer of 0 or more).
The defect list header 32 contains the number of the defect entries 33 contained in a DFL 15 and the like. The defect list header 32 is located at a predetermined position in the DFL 15 (e.g., the beginning of the DFL 15).
The defect entry 33 contains positional information about a defect block detected in the data area 5; replacement block positional information about a spare area which replaces the defect block; and the like.
The DDS 14 contains defect list beginning positional information indicating the position of the DFL 15, and the like.
The DMA1 to the DMA4 contained in the rewritable optical disc 400 are rewritable. Therefore, every time defect management information is updated, latest defect management information can be written over the DMA1 to the DMA4, i.e., updates can be performed. Thus, latest defect management information can be consistently recorded in the DMA1 to the DMA4 at the fixed positions.
FIG. 24 shows the structure of a conventional rewritable optical disc recording/reproduction apparatus 200.
The optical disc recording/reproduction apparatus 200 is connected via an I/O bus 170 to a higher level control apparatus (not shown). The higher level control apparatus is typically a host computer.
The optical disc recording/reproduction apparatus 200 comprises: a command processing section 110 for processing a command from the higher level control apparatus; a recording control section 120 for controlling recording of an optical disc; a reproduction control section 130 for controlling reproduction of an optical disc; a defect management information storage buffer 140 for storing contents reproduced from any one of the DMA1 to the DMA4; a data buffer 150 for temporarily storing recorded data and reproduced data; and a defect management information processing section 180 for performing processing relating to defect management information.
The defect management information processing section 180 comprises: a defect management information reading section 161 for detecting a normal defect management area from the DMA1 to the DMA4 and reading and transferring contents from the normal defect management area to the defect management information storage buffer 140; a defect management information updating section 164 for, when defect block information has been changed, updating the contents of the defect management information storage buffer 140 to create new defect information; a defect management information writing section 162 for writing the contents updated by the defect management information updating section 164 to the DMA1 to the DMA4; and a defect management information control memory 163 for storing an operational control state of the defect management information processing section 180.
However, information can be recorded into the DMA1 to the DMA4 of a write-once read-many information recording medium (write-once read-many optical disc) only once. Therefore, in the case of write-once read-many information recording media, it is not possible that latest defect management information is consistently recorded at a predetermined position in the DMA1 to the DMA4 as in rewritable information recording media (rewritable optical discs). Therefore, recording/reproduction apparatuses for rewritable information recording media cannot perform recording/reproduction on write-once read-many information recording media capable of defect management.
The present invention is provided to solve the above-described problems. An object of the present invention is to provide a write-once read-many information recording medium on which recording/reproduction can be performed by a recording/reproduction apparatus for rewritable information recording media; an information recording method for recording information onto the write-once read-many information recording medium; an information reproduction method for reproducing information from the write-once read-many information recording medium; an information recording apparatus for recording information onto the write-once read-many information recording medium; and an information reproduction apparatus for reproducing information from the write-once read-many information recording medium.